how much longer has she got till she goes into labour

Question
HI, A friend of mine recently split with her husband and gave me her cat as she said she couldn't cope. Dusty (the cats name), was pregnant when i took her on the 17th April, (She had just started to show).My friend did not have a clue when dusty got pregnant so i don't know how far gone she is. I've known dusty since she was a kitten so she has settled in with me and my family very well. She has had a litter of 3 kittens before (i think it was around July or august last year) and that pregnancy and birth went fine. I have had her now for about 5 weeks, and everyday lately im thinking this is it.  She must be close as she is gigantic, for the past week now i have seen a few times a little jelly stringy looking stuff coming from her you know what (not a large amount just a little). I have put boxes and opened cupboards for her all round the house and she has been in all of them and dug about as if making a nest. I don't know what to expect as ive never had a pregnant cat before, i have had my other cats neutered and so will dusty be after. I was a little concerned as she had a little bit of runny poo last night and again this morning and it also had a very small amount of blood in it.
Before that her poo has been fine. As well as dried food i feed my cats whiskers and she had been eating that since she come to live with me,but Friday last week i thought id treat her and spent quite a bit of money on really nice food for her instead of whiskers (could this food be to rich for her maybe and that is whats causing the runny poo?). I have only fed her the dried food since i noticed she had the runs last night and she hasn't been since about 8.30 this morning, am i doing the right thing?. The only reason i have not yet taken her to the vet is that she still is eating and drinking and the kittys are still moving about in her belly other than that all she does is sleep. One more thing i was curious about is since Saturday when you stroked her and got near her back end above her tail, she stuck her bum in the air as if she was in heat is that normal because she hadn't done it before?. Sorry to babble on but we have got so attached to each other in these past few weeks its as if its my daughter having the babys. Also i think her belly looks like it is sitting a bit lower since the weekend.
any info would be gratefully appreciated
leanne

Answer
Hi Leanne, thank you for all the detail in your letter. I would say Dusty is due YESTERDAY>>> ha ha
Seriously she is due any minute. When they put their tail in the air like that it is because the kittens are pushing on her and now if her tummy is a little softer and has dropped she will have those kittens anytime. I know it is easy to be nervous but if she has had kittens before she will probably be just fine ! the reason she had some stool problems is probably because you are changing her food more than the idea that it is too rich. Any changes to the diet should be done slowly over a week or 10 days... but I think you are on the right track.If she is having a litter it would be perfect to get her onto some high quality food that will give her and her kittens more nutritional value. Just do it slowly.. a bit of the new stuff every day.
So, try to stick around the house today if you can as I think you are going to be a granny soon.. and NO>> this is nothing like when your daughter does it !!! ARGH>> that was VERY scary for me.. LOL
Teresa